Half-sine wave pulse generator using shock excited resonant circuit discharging through a thyratron



Jan. 21, 1964 A. ROSENTHAL 3,119,068

HALF-SINE WAVE PULSE GENERATOR USING SHOCK EXCITED RESONANT CIRCUIT DISCHARGING THROUGH A THYRATRON Filed Aug. 20, 1957 FIG.1.

T NATOR DE 0 AMPLITUDE INVENTOR. iOUIS A. ROSENTHAL ATTYS.

United States Patent 3,119,06fi HALF-SHNE WAVE PULSE GENERATGR USING SHOCK EXCITED RESONANT CIRCUIT DIS- CHARGKNG THROUGH A THYRATRON Louis A. Rosenthal, Highland Park, NJ, assignor to the United States of America as represented by the Secretary of the Navy Filed Aug. 2t), 1957, Ser. No. 679,327 9 Claims. (Cl. 32834) This invention relates generally to impulse generating circuitry and more particularly to a half-sine wave impulse generator circuit.

In the majority of pulse testing techniques the generated impulses utilized in the test have a rectangular waveform; however, there are testing applications wherein other waveforms are acceptable with a concomitant simplification in the impulse generating circuitry. An exemplary application exists in the experimental study of the ignition characteristics of electroresponsive ordnance primers and detonators wherein it is merely necessary to employ an electrical firing impulse having a known energy content. To satisfy this requirement, the employment of half-sinusoidal firing or initiating impulses has been found to be satisfactory.

Accordingly, a principal object of the instant invention is the provision of a new and improved energy impulse generator.

Another object of the present invention is to provide a new and improved half-sine pulse energy source.

A further object of the instant invention is the provision of a novel half-sinusoidal waveform generating circuit.

A still further object of the present invention is to provide a new and improved simple circuit for the production of half-sine impulses of variable energy content.

Another still further object of the instant invention is the provision of a pulsing circuit adapted to provide a single or a repetitive series of pulses, each pulse having a known energy content.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the sam becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein:

FIG. 1 is a schematic circuit diagram of the impulse generator in accordance with the instant invention; and

FIG. 2 illustrates certain impulse waveforms generated by the circuit of FIG. 1.

This invention relates to a variable half-sine wave generator that may be used in the experimental study of the ignition characteristics of explosive ordnance primers and detonators. The output of the half-sine wave generator is variable both in the rate of actuation and in energy content of the actuated impulse. The energy output may be varied selectively either by changing the input voltage or by variation of the parameters in the resonant circuit. In either case the energy content of the output impulse may be determined prior to actuation. In this manner the ignition characteristics of the various ordnance primers may be explored without detonation.

Referring now more particularly to FIG. 1, the componential triggering circuit, half-sine wave generator, and power supply circuit are generally indicated by reference numerals ll, 12 and 13, respectively. As shown, power supply 13 includes a power transformer 14 having a primary winding 15 connectable to a line supply, such for example as a 60 c.p.s., 117 V. AC. single phase line, and a plurality of secondary windings; namely a centertapped high voltage winding 16 and a pair of filament voltage windings l7 and 18. Connected across the winding 16 are the plates of a full-wave rectifier tube 19 for converting the AC. line potential into a pulsating unidirectional potential. A smoothing capacitor 21 is connected between ground, or common, 22 and the cathode of the rectifier tube 19. Connected across capacitor 21 are a current limiting resistor 23 and a pair of serially connected voltage regulator tubes 24 and 25. A current dividing network consisting of serially connected resistors 26 and 27 is connected across the tubes 24 and 25, the common junction of said tubes being connected to the common junction of said resistors. It will be apparent to one skilled in the art that a regulated DC. potential will be available at circuit junction 28. A series control tube 29 and resistor 31 are connected across the junction 28 and ground 22. The level of the D.C. potential appearing at circuit junction 32 may be adjusted to a desired level by means of potentiometer 33 having the movable tap thereof connected to the control grids of tube 2? thereby to control the grid bias thereof. The purpose of this adjustable feature of the power supply circuit will be more fully described hereinafter. Suitable heater current is provided for the series control tube by filament winding 18. Filament winding 17 is connected through rectifier element 34 to potentiometer 35 thereby to provide a source of variable negative unidirectional potential at the movable contact thereof. A suitable filter capacitor 36 is shunt connected across potentiometer 35 to smooth out the rectified potential. The purpose of this negative potential source will be further described.

The half-sine impulse generator 12 includes a gas tube 37, such for example as a 2D21 thyratron, having a series resonant network consisting of inductance 38 and capacitor 39 connected between ground 22 and the plate of tube 37. The plate of tube 37 is also connected to the variable DC. potential available at circuit junction 32 of the electronic power supply 13 through isolation rcsistor ll. The generator circuit is normally maintained in an unactuated state by impressing upon the gas tube control grid a biasing potential from potentiometer 35 through grid resistor 42 of sufiicient magnitude to maintain the gas tube non-conductive. A pair of terminals 43 is provided in the circuit between ground 22 and the cathode of the gas tube for reception of the load 44, such for example as an electroresponsive primer, to which the developed energy burst is to be applied.

For the purpose of actuating the impulse generating circuit, the gas tube control grid is connected through isolation resistor 45 to a two position selector switch 46 of the triggering circuit ll. When switch 46 is operated to position a, it serves to couple gas tube 37 to a oneshot triggering circuit 47, and when operated to position b, the gas tube is coupled to a sequential triggering circuit 48 thereby providing for repetitive pulsing of generating circuit 12. As shown on PEG. 1, the one-shot circuit 4-7 includes a plurality of parallel connected branch circuits respectively indicated by reference numerals 4 9, 5-1 and 52. Circuit 49 consists of a capacitor 53 normally maintained at a charge level insutficient to break down the neon gas tube 54 serially connected with current limiting resistor 55 in branch circuit 52 by means of discharge limiting resistor 56 and normally closed pushbutton switch 57 disposed in branch circuit 51. Upon momentary opening of switch 57, capacitor 53 is chargeable through isolating resistor 58 from the regulated DC. potential appearing at circuit junction 28. The charge upon capacitor 53 gradually builds up until it exceeds the breakdown level of gas diode 54 whereupon the instantaneous tube vo-ltage drop from the ignition potential level to the maintaining potential level results in the generation of a pulse across resistor 55. The pulse is differentiated by passing through a small coupling capacitor 59 and thereupon is impressed upon the control grid electrode of thyratron 37.

The sequential triggering circuit '48 includes a neon diode 61 connected through a dropping resistor 62 to one terminal of secondary winding 16. In response to the line frequency potential impressed across it, gas tube 61 ignites and the resultant tube voltage drop signal is passed through a small coupling capacitor 63 to the grid electrode of thyratron 37. The amplitude of the differentiated signal developed by either the one-shot trigger circuit 47 or the sequential trigger circuit 48 is of suificient amplitude to ignite thyratron 37 thereby resulting in the actuation of impulse generating circuit 12.

The operation of the circuit will now be more clearly described. Inasmuch as thyratron 37 is normally biased to cut-oil, capacitor 39 will charge to the potential available at circuit junction 32, anticipating ignition of thyratron 37. Upon the application of a suitable positive triggering signal to the thyrstron control grid from either the oneshot circuit 47 or the multiple trigger circuit 43, the thyratron will ignite and the charged capacitor will discharge through inductor 3S and thyratron 37 into the load device 44 arranged in the cathode circuit of the thyratron. Although theoretically, the energy exchange in the resonant circuit will be in the form of a damped sinusoidal oscillation, only the first positive half-cycle of the discharge actually occurs inasmuch as the thyratron will be quenched upon the first negative half-cycle thereby terminating the oscillation. z ioreover, it will be obvious to one skilled in the art to which the instant invention pertains that the amplitude and width of the halfsine pulse impressed across load 44 can be controlled by variation of the supply potential at circuit junction 32 and by variation of the magnitudes of either coil 38 or capacitor 39.

Waveforms 64 of FIG. 2 illustrate the variation in the generated half-sine wave impulse resulting from varia- [ions of the hereinbefore recited circuit parameters.

It wiil be understood that if the resistance of the load 44 is known and of substantially constant magnitude, the energy delivered to the load by each half-sine wave impulse can be determined by the well known equation E=i RT, wherein R designates the resistance of the load 44 connected between output terminals 43, i is the root mean square value of the current passing through the resistive load 44 under repetitive operation, and T is the period of the repetition [i.e. ,4, second].

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. An unidirectional impulse generating apparatus for determining the ignition characteristics of an eleotroresponsive detonating device comprising normally unactuated oscillatory circuit means for developing a half-sine wave impulse across an electroresponsive detonating device upon application of an initiating signal thereto, said circuit means including a tunable resonant network for controlling the energy content of the impulse, first circuit means for developing a solitary initiating signal, second circuit means for developing a repetitious series of initiating signals, circuit selector means for alternatively connecting said oscillatory circuit means to a selected one of said first and second circuit means, and energizing circuit means for providing suitable energizing potentials for said first, second and oscillatory circuit means, said energizing circuit means also including means for selectively controlling the amplitude of the unidirectional impulse.

2. Apparatus according to claim 1 wherein the resonant network includes a serially connected capacitor and inductor.

3. An unidirectional impulse generating electrical apparatus for determining the ignition characteristics of a detonating device comprising normally unactuatcd oscillatory circuit means for producing a half sinusoidal waveform energy burst upon application of a triggering signal thereto, said circuit means including an adjustable resonant frequency network for selectively varying the magnitude of said energy burst, a potential energy source, a multiple triggering signal generating circuit including a normally non-conducting first gas tube coupled to said source and being adapted to be rendered sequentially conductive thereby, a single triggering signal generating circuit including an energy storage device adapted to being charged by said source, a normally non-conducting second gas tube coupled across said storage device and being adapted to be rendered conductive by the charge thereon, and a circuit selector switch coupled to said oscillatory circuit means for selectively coupling said single and multiple signal generating circuits to said circuit means thereby to render said circuit means actuated.

4. Apparatus according to claim 3 wherein said potential energy source includes circuit means for selective ly controlling the amplitude of said produced energy burst.

5. An electrical impulse generator comprising, a supply of a plurality of unidirectional and alternating potentials; an oscillatory circuit coupled to said supply, said circuit including a serial connected first gas discharge device having at least an anode, cathode, and control grid, a series resonant network having one end thereof connected to said anode and to a first one of said unidirectional potentials, load receptive terminals interconnecting the other end of said resonant network and said cathode, a resistive circuit path interconnecting said control grid and a second one of said unidirectional potentials for normally maintaining said first gas discharge device nonconductive; a source of a single impulse signal suitable for rendering said first gas discharge device conductive, said source including an energy storage device resistively coupled to a third one of said unidirectional potentials and chargeable therefrom, a shorting circuit connected across said energy storage device for effecting charging thereof upon interruption of said shorting circuit, and a serially connected resistance and second gas discharge device connected across said energy storage device for generating a positive potential signal in response to the charge on said energy storage device; a source of a series of impulse signals each of which is suitable for rendering said first gas discharge device conductive, said last recited source including a third gas discharge device resistively connected to one of said alternating potentials and being intermittently rendered conductive thereby, a selector switch coupled to said control grid for selectively and alternatively connecting said sources to said oscillatory circuit thereby to render said first gas discharge device conductive for developing a half-sine wave energy impulse across said load receptive terminals, and means included in said supply and said resonant network for selectively varying the magnitude of said half-sine wave energy impulse.

6. A device for testing detonators comprising a plurality of unidirectional and alternating potentials, it normally unactuated oscillatory circuit means for producing a half sinusoidal Waveform energy burst upon application of a triggering signal thereto, said circuit means including an adjustable resonant frequency network for selectively varying the magnitude of said energy burst, a first one of said unidirectional potentials connected to said circuit means, detonator means electrically connected in said circuit means and responsive to said energy burst, a single triggering signal generating circuit including a normally non-conducting first gas tube coupled across an energy storage device and being adapted to be rendered conductive by a charge thereon, said storage device being resistively coupled to a second one of said unidirectional potentials and chargeable therefrom, a multiple triggering signal generating circuit including an energy storage device adapted to be charged by a third one of said unidirectional potentials, a normally non-conducting second gas tube coupled to said storage device and being adapted to be rendered conductive by a charge thereon, and a circuit selector switch coupled to said oscillatory circuit means for selectively and alternatively coupling said signal generating circuits to said circuit means thereby to render said circuit means actuated.

7. The device of claim 6 wherein the oscillatory circuit means includes a serially connected gas discharge device having at least an anode, cathode, and control grid, said gas discharge device being connected in a closed loop with said detonator means and said resonant frequency network, and said selector switch being connected to said control grid.

8. An electrical impulse generator comprising an oscil latory circuit means for developing a half-sine wave impulse across an electroresponsive detonating device upon application of an initiating signal thereto, means providing a plurality of unidirectional and alternating potentials, a first one of said uni-directional potentials being con nected to said oscillatory circuit means, a source of a single impulse signal suitable for rendering said oscillatory circuit means conductive, said source including an energy storage device resistively coupled to a second one of said unidirectional potentials and chargeable therefrom, a shorting circuit connected across said energy storage device for effecting charging thereof upon interruption of said shorting circuit, a serially connected resistance anode, a second gas discharge device connected across said energy storage device for generating a positive potential signal in response to the charge on said energy storage device, a source of a series of impulse signals each of which is suitable for rendering said oscillatory circuit conductive, said last recited source including a second gas discharge device resistively connected to the source of one of said alternating potentials and being intermittently rendered conductive thereby, a selector switch coupled to said oscillatory circuit means for selectively and alternatively connecting said sources to said oscillatory circuit means thereby rendering said oscillatory circuit means conductive for developing a half-sine wave energy impulse across said detonating device, and means included in said oscillatory circuit means for selectively varying the magnitude of said half-sine Wave enengy impulse.

9. An electrical impulse generator of claim 8 wherein the oscillatory circuit means comprise a gas discharge device having at least an anode, cathode and control grid, a series resonant network having one end connected to said anode and to said first one of said unidirectional potentials, the other end being connected through said electroresponsive detonating device to said cathode, said source of signals being connected to said grid, and said means for varying the magnitude of said half-sine wave energy impulse comprise means for varying said first one of said unidirectional potentials and said resonant circuit network.

References Cited in the file of this patent UNITED STATES PATENTS 1,978,684 McCreary Oct. 30, 1934 2,415,302 Maxwell Feb. 4, 1947 2,416,111 Maxwell Feb. 18, 1947 2,464,279 Zarem et al Mar. 15, 1949 2,495,780 Shepherd et a1 Ian. 31, 1950 2,575,559 Parkinson Nov. 20, 1951 2,591,511 Clarke Apr. 1, 1952 2,595,228 Crist May 6, 1952 2,606,289 Stanton Aug. 5, 1952 2,621,294 Podbienlniak Dec. 9, 1952 2,644,094 Douglas lune 30, 1953 2,693,532 Krienen Nov. 2, 1954 2,743,360 Stanton et a1 Apr. 24, 1956 2,764,689 Struven Sept. 25, 1956 2,869,364 Kabik et al Jan. 20, 1959 2,891,155 Carr et a1 June 1-6, 1959 FOREIGN PATENTS 422,809 Great Britain Jan. 18, 1935 

1. AN UNIDIRECTIONAL IMPULSE GENERATING APPARATUS FOR DETERMINING THE IGNITION CHARACTERISTICS OF AN ELECTRORESPONSIVE DETONATING DEVICE COMPRISING NORMALLY UNACTUATED OSCILLATORY CIRCUIT MEANS FOR DEVELOPING A HALF-SINE WAVE IMPULSE ACROSS AN ELECTRORESPONSIVE DETONATING DEVICE UPON APPLICATION OF AN INITIATING SIGNAL THERETO, SAID CIRCUIT MEANS INCLUDING A TUNABLE RESONANT NETWORK FOR CONTROLLING THE ENERGY CONTENT OF THE IMPULSE, FIRST CIRCUIT MEANS FOR DEVELOPING A SOLITARY INITIATING SIGNAL, SECOND CIRCUIT MEANS FOR DEVELOPING A REPETITIOUS SERIES OF INITIATING SIGNALS, CIRCUIT SELECTOR MEANS FOR ALTERNATIVELY CONNECTING, SAID OSCILLATORY CIRCUIT MEANS TO A SELECTED ONE OF SAID FIRST AND SECOND CIRCUIT MEANS, AND ENERGIZING CIRCUIT MEANS FOR PROVIDING SUITABLE ENERGIZING POTENTIALS FOR SAID FIRST, SECOND AND OSCILLATORY CIRCUIT MEANS, SAID ENERGIZING CIRCUIT MEANS ALSO INCLUDING MEANS FOR SELECTIVELY CONTROLLING THE AMPLITUDE OF THE UNIDIRECTIONAL IMPULSE. 